The objective of this research is to define the molecular-biochemical mechanism of how avion oncornavirus replicate and interact with cells. Specifically, we are studying the following: A. Purification and characterization of the enzymatic activity that catalyzes 'splicing' of RNA sequences in tumor virus mRNAs. B. Provide evidence that viral protein p19 functions in vitro to control processing of viral RNA. C. Isolate and sequence p19 binding sites on viral RNA. D. Isolate and determine the amino acid sequence of RNA binding site of the p19 protein.